Display control device

ABSTRACT

A display control device sets a display position of an image to be recognized by a driver of a vehicle as a virtual image such that the image is superimposed on a scenery in front of the vehicle. The display control device calculates a correction amount for correcting the display position at which the image is superimposed on the scenery.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of InternationalPatent Application No. PCT/JP2020/041081 filed on Nov. 2, 2020, whichdesignated the U.S. and claims the benefit of priority from JapanesePatent Application No. 2019-203975 filed on Nov. 11, 2019. The entiredisclosures of all of the above applications are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to a display control device that controlsan in-vehicle display or the like.

BACKGROUND

As a device that superimposes a virtual image on an object in a scenerythat can be seen through a windshield of a vehicle, a head-up displayhaving an Augmented Reality (AR) function (hereinafter referred to as anAR-HUD) is known.

SUMMARY

The present disclosure provides a display control device. The displaycontrol device sets a display position of an image to be recognized by adriver of a vehicle as a virtual image such that the image issuperimposed on a scenery in front of the vehicle. The display controldevice calculates a correction amount for correcting the displayposition at which the image is superimposed on the scenery.

BRIEF DESCRIPTION OF DRAWINGS

The features and advantages of the present disclosure will become moreapparent from the following detailed description made with reference tothe accompanying drawings. In the drawings:

FIG. 1 is a block diagram showing a configuration of an informationdisplay system;

FIG. 2 is an explanatory diagram showing a projection area;

FIG. 3 is an explanatory diagram showing an arrangement and the like ofa HUD device;

FIG. 4 is a block diagram functionally showing a configuration of adisplay control device;

FIG. 5 is an explanatory diagram showing a change in a voltage signalwhen a moving average filter is used;

FIG. 6 is a flowchart showing a main processing executed by the displaycontrol device;

FIG. 7 is a flowchart showing a processing for calculating a correctionamount of a display position executed by the display control device;

FIG. 8 is an explanatory diagram showing a relationship between a changein pitch angle and deviation of eye positions and superimposed displaypositions on a HUD display surface;

FIG. 9 is an explanatory diagram showing a relationship between thedeviation of eye positions and superimposed display positions on the HUDdisplay surface;

FIG. 10 is an explanatory diagram showing a simple model showing arelationship between a detection value of a height sensor and a vehiclepitch angle; and

FIG. 11 is an explanatory diagram showing a relationship between avehicle speed and a pitch angle.

DETAILED DESCRIPTION

In an AR-HUD, there is a difficulty that a superimposed position of avirtual image in a scenery shifts due to a change in a pitch angle or aroll angle of a vehicle.

As a countermeasure, the pitch angle or roll angle may be detected by anangular sensor, a vehicle posture may be estimated based on the detectedangle, and an angle of a mirror that projects an image and a displayposition may be adjusted. Thereby, a misalignment of the virtual imagemay be suppressed.

As a result of detailed examination by the inventors, the followingdifficulty was found.

For example, a vehicle posture (for example, a pitch angle) is estimatedaccording to an output value (that is, a sensor value) of a pitch anglesensor, and then the display position is corrected. However, in atraveling state, the sensor value often changes quickly. In such a case,in the above conventional technique, the display position also changesquickly, so that the display of the virtual image may be flickering anddifficult to see.

As a countermeasure, it is conceivable to apply a low-pass filter (thatis, LPF) to a sensor value to slowly change the sensor value. However,in this case, the followability when correcting the display position islowered. Therefore, the state in which the superimposed position of thevirtual image is displaced becomes long, and there is a possibility thatrecognition of a displayed content is deteriorated, particularly in atraveling state.

As described above, it has been found that it is not easy to achieveboth suppression of display flicker on an in-vehicle display and quickcorrection of display position.

The present disclosure provides a display control device capable ofsuppressing display flicker on an in-vehicle display or the like andquickly correcting a display position.

An exemplary embodiment of the present disclosure provides a displaycontrol device. The display control device includes an informationgeneration unit, a traveling state acquisition unit, a posture valueacquisition unit, a characteristic acquisition unit, a filter processingunit, and a display position correction unit. The information generationunit is configured to set a display position of an image, as a virtualimage, to be recognized by a driver of a vehicle such that the image issuperimposed on a scenery in front of the vehicle. The image beingdisplayed on a display unit that is disposed in front of a driver seatof the vehicle and enables the driver to recognize the scenery. Thetraveling state acquisition unit is configured to acquire a travelingstate of the vehicle. The posture value acquisition unit is configuredto acquire a vehicle posture value indicating a posture of the vehicle.The characteristic acquisition unit is configured to acquire a vehiclecharacteristic value indicating a characteristic of the vehicle from acharacteristic storage unit that stores the vehicle characteristicvalue. The filter processing unit is configured to perform a filterprocessing with a filter on the vehicle posture value acquired by theposture value acquisition unit. The display position correction unit isconfigured to calculate a correction amount for correcting the displayposition at which the image is superimposed on the scenery based on thevehicle characteristic value processed by the filter processing unit andthe vehicle characteristic value acquired by the characteristicacquisition unit. The filter processing unit sets a characteristic ofthe filter according to the traveling state of the vehicle acquired bythe traveling state acquisition unit, and performs the filter processingwith the set filter.

In the exemplary embodiment of the present disclosure, when thecorrection amount of the display position is calculated and the displayposition is corrected based on the vehicle posture value processed bythe filter processing unit and the vehicle characteristic value, thevehicle posture value, in which the filter processing is performed withthe filter set according to the traveling state of the vehicle. That is,when the display position is corrected, the vehicle posture valueappropriately filtered according to the traveling state of the vehiclecan be used.

Therefore, when the image to be recognized as a virtual image on thedisplay unit is superimposed on the scenery, the configuration cansuppress display flicker and quickly correct the display position. Thatis, the configuration can suppress flickering of the display on thein-vehicle display or the like and quickly correct the display position.

For example, when the vehicle is in the acceleration state, a filterhaving a large time constant is adopted as compared with the case wherethe vehicle is in the stopped state or the constant speed travelingstate. Thus, the configuration, in the acceleration state, can suppressthe flickering of the display, and the configuration, in the stoppedstate or the like, can quickly correct the display position.

Hereinafter, exemplary embodiments for implementing the presentdisclosure will be described with reference to the drawings.

[1. Embodiment]

[1-1. Overall Configuration]

First, the overall configuration of an information display systemincluding a display control device of the present embodiment will bedescribed.

As shown in FIG. 1, the information display system 1 is mounted on, forexample, a vehicle 2 shown in FIG. 2. Hereinafter, the vehicle 2equipped with the information display system 1 may be referred to as asubject vehicle 2.

The information display system 1 includes a display control device 3.Further, the information display system 1 may include a peripheralmonitoring unit 5, a behavior detection unit 7, a driver detection unit9, a map storage unit 11, a positioning unit 13, a navigation device 15,a characteristic storage unit 17, and a head-up display (hereinafter,HUD) device 19. The map storage unit 11 is also referred to as a mapstorage, and the characteristic storage unit 17 is also referred to as acharacteristic storage.

Each unit constituting the information display system 1 may transmit andreceive information via an in-vehicle LAN. LAN is an abbreviation forLocal Area Network.

As shown in FIG. 2, in the information display system 1, the HUD device19 projects an image onto a projection area 23 of a windshield 21located in front of the driver's seat, so that the information displaysystem 1 displays various information through the windshield 21 bysuperimposing an actual scenery that is visually recognized by thedriver. The projection area 23 is also referred to as a display unit. Inthe following, an image superimposed on such an actual scenery isreferred to as an AR image. AR is an abbreviation for Augmented Reality.That is, here, as the HUD device 19, a head-up display (that is, AR-HUD)device having the above-mentioned AR function is used.

As shown in FIG. 1, the peripheral monitoring unit 5 includes at leastone of a radar sensor and a camera. The radar sensor uses infrared rays,millimeter waves, ultrasonic waves, or the like as radar waves, anddetects distance from a target that reflects the radar wave, directionin which the target exists, and the like. As the camera, a visible lightcamera, an infrared camera, or the like is used. The camera is arrangedso as to include a region (hereinafter referred to as a visible region)visually recognized by the driver through the windshield 21 as animaging range. Similar to the camera, the radar sensor is arranged so asto include the visible region as the detection range.

The peripheral monitoring unit 5 detects a target existing on thetraveling path of the vehicle (for example, the subject vehicle) 2 witha radar sensor and a camera, and generates target information includingthe position of the detected target. The detection target of theperipheral monitoring unit 5 includes, for example, various targets tobe processed by the advanced driver assistance system (that is, ADAS).ADAS is an abbreviation for advanced driver assistance system. Theperipheral monitoring unit 5 may generate the target informationincluding the position of the target based on the map information storedin the map storage unit 11 described later.

The behavior detection unit 7 outputs various signals indicating adriving operation by the driver, a signal indicating the behavior of thevehicle 2 as a result of the driving operation, and a signal indicatingthe state of the vehicle 2 affecting the behavior of the vehicle 2.Includes sensor.

For example, the behavior detection unit 7 includes a vehicle speedsensor 31, an acceleration sensor 33, sensors 35 for detecting outputtorque, a height sensor 37, and the like.

The vehicle speed sensor 31 is a sensor that detects a speed of thevehicle 2.

The acceleration sensor 33 is a sensor that detects the front-rearacceleration of the vehicle 2.

The sensors 35 have various sensors for detecting various signals forcalculating the output torque of the tire (that is, the tire output).Examples of the sensors 35 include, for a case of the vehicle 2 drivenby an internal combustion engine (that is, an engine), various sensorsthat detect the amount of fuel, the amount of air, and the like suppliedto the engine. The output torque of the engine, and therefore the outputtorque of the tire, can be calculated from the sensor value output fromeach sensor.

Further, examples of the sensors 35 include, for a case of the vehicle 2driven by electricity, various sensors that detects the voltage andcurrent of electricity supplied to the motor for driving the tire. Then,the output torque of the tire can be calculated from the sensor valueoutput from each sensor.

The height sensor 37 is provided on any of the wheels (for example,front wheel or rear wheel) of the vehicle 2 and outputs a detectionsignal according to the relative displacement amount (hereinafter,vehicle height detection value) H between the axle of the wheel and thevehicle body. That is, the height sensor 37 is a change amount detectionunit that detects the change amount of the vehicle height. The vehicleheight detection value H includes the displacement amount of thesuspension. In this embodiment, the height sensor 37 is provided, forexample, on the right rear wheel.

In addition to the sensors 33 to 37, the behavior detection unit 7 mayinclude, for example, an accelerator pedal sensor, a brake pedal sensor,a steering angle sensor, a direction indicator switch, a yaw ratesensor, and the like.

The driver detection unit 9 is a device that detects a driver's statesuch as a face position, a face direction, an eye position, and aline-of-sight direction based on a driver's face image captured by anin-vehicle camera. Based on the signal from the driver detection unit 9,it is possible to acquire position information (that is, eyeinformation) indicating the positions of the eye in the verticaldirection and the front-rear direction, as will be described later. Thedriver detection unit 9 is known as a so-called driver status monitoring(that is, DSM) system.

Map information, AR information, and the like are stored in the mapstorage unit 11. The map information is used for route guidance by thenavigation device 15 and for superimposing an AR image on an actualscenery.

The map information includes, for example, information on roads,information on lane markings such as white lines and road markings, andinformation on structures. The information on the roads includes shapeinformation such as position information for each point, curve curvatureand slope, and connection relationship with other roads. The informationon the lane markings and road markings includes, for example, typeinformation of lane markings and road markings, location information,and three-dimensional shape information. The information on thestructures includes, for example, type information, positioninformation, and shape information of each structure. Here, thestructure includes, for example, road signs, traffic lights, streetlights, tunnels, overpasses, buildings facing the road, and the like.

The map information includes the above-mentioned position informationand shape information in the form of point group data, vector data, orthe like of feature points represented by three-dimensional coordinates.That is, the map information represents a three-dimensional mapincluding altitude in addition to latitude and longitude with respect tothe position information. Therefore, from the map information, it ispossible to extract information on the slope of the road at each pointon the road, specifically, a longitudinal slope along the travelingdirection of the road and a cross slope along the width direction of theroad. The location information included in the map information has arelatively small error on the order of centimeters. The map informationis highly accurate map data in that it has position information based onthree-dimensional coordinates including height information, and it isalso highly accurate map data in that the error in the positioninformation is relatively small.

The AR information is data used for displaying an AR image, and includessymbols, characters, icons, and the like that are superimposed anddisplayed on the background (that is, the actual scenery). The ARinformation may include information for route guidance linked with thenavigation device 15 (for example, an arrow superimposed on the roadsurface).

The positioning unit 13 is a device that generates position informationfor identifying the current position of the vehicle (for example, thesubject vehicle) 2. The positioning unit 13 includes, for example, aGNSS receiver and sensors for autonomous navigation such as a gyroscopeand a distance sensor. The GNSS stands for Global Navigation SatelliteSystem. The GNSS receiver receives a transmission signal from theartificial satellite and detects the position coordinates and altitudeof the subject vehicle 2. The gyroscope outputs a detection signalaccording to the angular velocity of the rotational motion applied tothe subject vehicle 2. The distance sensor outputs the mileage of thesubject vehicle 2.

The positioning unit 13 calculates the current position of the subjectvehicle 2 based on the output signals from these devices. Thepositioning unit 13 generates highly accurate position information andthe like of the subject vehicle 2 by combined positioning that combinesthe information from the GNSS receiver and the information from thesensor for autonomous navigation. The positioning unit 13 has theaccuracy of identifying the lane in which the subject vehicle 2 travelsamong the plurality of lanes, for example.

The navigation device 15 provides route guidance based on the currentposition of the subject vehicle 2 and the map data. The navigationdevice 15 identifies the current position and the traveling direction ofthe subject vehicle 2 on the road by the positioning result of thepositioning unit 13 and the map matching using the map data. Thenavigation device 15 provides the display control device 3 with the mapinformation, AR information, and the like regarding the current positionand traveling direction of the subject vehicle 2, the route to thedestination, the roads and facilities existing in the visual area of thedriver, and the like.

The characteristic storage unit 17 includes a non-volatile memory. Thecharacteristic storage unit 17 stores a vehicle characteristic value(that is, characteristic information) G used at the time of conversionfrom the detection value (that is, the vehicle height detection value) Hof the height sensor 37 to a vehicle pitch angle θ. The vehicle pitchangle θ is an inclination angle of the vehicle body in the front-reardirection with respect to the horizontal plane.

As shown in FIGS. 2 and 3, the HUD device 19 is arranged in theinstrument panel 41. The HUD device 19 includes a projector 43 and anoptical system 45. The projector 43 includes a liquid crystal display(hereinafter referred to as LCD) panel and a backlight. The projector 43is fixed in a position at which the display screen of the LCD panel isdirected toward the optical system 45. The projector 43 displays animage on the LCD panel according to an instruction from the displaycontrol device 3, transmits light by a backlight, and emits light formedas a virtual image toward the optical system 45.

The optical system 45 has at least a mirror 47 (for example, a concavemirror), and projects onto a certain projection area 23 by reflectingand magnifying the light emitted from the projector 43 in a region onthe windshield 21 set in the driver's viewing region. As a result, theAR image as shown by Vi in FIG. 3 is superimposed and displayed on theactual scenery in the visible area of the driver.

[1-2. Display control device]

Next, the display control device 3 will be described in detail.

As shown in FIG. 1, the display control device 3 includes amicrocomputer 50 having a CPU 51 and, for example, a semiconductormemory 53 such as a RAM 53 a, a ROM 53 b, and a flash memory 53 c. Eachfunction of the display control device 3 is realized by the CPU 51executing a program stored in a non-transitional tangible recordingmedium (for example, a semiconductor memory 53). The display controldevice 3 is also called an HCU. HCU is an abbreviation for HMI ControlUnit, and HMI is an abbreviation for Human Machine Interface.

As shown in FIG. 4, the microcomputer 50 of the display control device 3includes, as functional configurations realized by executing a programstored in the semiconductor memory 53, an information generation unit61, a traveling state acquisition unit 63, a posture value acquisitionunit 65, a characteristic acquisition unit 67, a filter processing unit69, an eye information acquisition unit 71, and a display positioncorrection unit 73.

The information generation unit 61 sets the display position (that is,the projection position) in the projection area 23 of the windshield 21such that the AR image to be recognized as the virtual image to thedriver is superimposed on the scenery. The projection area 23 isdisposed in front of the driver seat of the vehicle 2 and enables thedriver to recognize the scenery in front of the vehicle 2.

Specifically, the information generation unit 61 defines the region inthe windshield 21 of the vehicle 2 on which the AR image to berecognized as the virtual image by the driver is projected as theprojection region 23. Further, through the projection area 23,information on an object (for example, a road) existing in the sceneryvisible to the driver is acquired. Then, the projection position in theprojection area 23 of the superimposed image (that is, the AR image)superimposed on the object is set according to the three-dimensionalposition information of the object.

The traveling state acquisition unit 63 is configured to acquire thetraveling state of the vehicle 2. The traveling state acquisition unit63 detects the traveling state of the vehicle 2 based on the signalsfrom the vehicle speed sensor 31, the acceleration sensor 33, and thesensors 35 for detecting the output torque in the behavior detectionunit 7. That is, the traveling state acquisition unit 63 is capable ofdetermining whether the traveling state of the vehicle 2 is a stoppedstate, a constant speed traveling state, or an acceleration state.

For example, when determining that the vehicle speed is 0 or 4 m/s orless based on the signal from the vehicle speed sensor 31, the travelingstate acquisition unit 63 determines that the vehicle is in the stoppedstate. Further, when determining that the change in vehicle speed withina predetermined time is within a predetermined value based on the signalfrom the vehicle speed sensor 31, the traveling state acquisition unit63 determines that the vehicle is in the constant speed traveling state.

Further, when determining, based on the signal from the vehicle speedsensor 31, that the absolute value of the change in vehicle speed withina predetermined time is equal to or greater than a predetermineddetermination value, the traveling state acquisition unit 63 determinesthat the vehicle is in the acceleration state. Further, when determiningthat the absolute value of the front-rear acceleration of the vehicle 2is equal to or higher than a predetermined determination value based onthe signal from the acceleration sensor 33, the traveling stateacquisition unit 63 determines that the vehicle is in the accelerationstate. Further, when the output torque is calculated based on the signalfrom the sensor 35 for detecting the output torque and the absolutevalue of the change in the output torque is determined to be equal to orhigher than a predetermined determination value, the traveling stateacquisition unit 63 determines that the vehicle is in the accelerationstate. The values of the respective determination values are different.

Here, the acceleration state includes both a case of having a positiveacceleration and a case of having a negative acceleration (that is, acase of a deceleration state).

The posture value acquisition unit 65 is configured to acquire a vehicleposture value indicating the posture of the vehicle 2. In the presentembodiment, as the vehicle posture value, a signal (that is, vehicleheight detection value H) indicating the height (that is, vehicleheight) of the vehicle 2 obtained from the height sensor 37 is used.

That is, the posture value acquisition unit 65 acquires the vehicleheight detection value H, specifically, the displacement amount of thesuspension, based on the signal from the height sensor 37.

The characteristic acquisition unit 67 is configured to acquire thevehicle characteristic value G indicating the characteristics of thevehicle 2 from the characteristic storage unit 17 that stores thevehicle characteristic value G. The vehicle characteristic value G is acharacteristic value used when calculating the vehicle pitch angle θ, aswill be described later. Examples of the vehicle characteristic value Ginclude the wheelbase, the distance from the front wheel to the positionof the center of gravity of the load applied to the vehicle 2, thespring constants of the front and rear suspensions, and the like.

The filter processing unit 69 is configured to filter a signalindicating the vehicle posture value (that is, the vehicle heightdetection value H) and a signal indicating the eye information.

In the present embodiment, as the filter used for the filter processing,for example, a well-known moving average filter represented by thefollowing formula (1) is used.

$\begin{matrix}( {{Equation}1} ) &  \\\begin{matrix}{{y\lbrack i\rbrack} = \frac{\sum_{n = 0}^{L - 1}{x\lbrack {i - n} \rbrack}}{L}} \\{= {\sum\limits_{n = 0}^{L - 1}\{ {\frac{1}{L} \cdot {x\lbrack {i - n} \rbrack}} \}}}\end{matrix} & (1)\end{matrix}$

In formula (1), y [i] represents the output at the time point i, x [i-n]represents the input at the time point i-n, and i and n representpositive integers. L represents the number of samples and corresponds tothe time constant.

By using this moving average filter, for example, as shown in FIG. 5,the high frequency component of the sensor signal of the voltage, whichis an input value, is suppressed, and an output value with reducedresponsiveness can be obtained. Note that 10 msec indicates a period inwhich the moving average is taken.

In this embodiment, as will be described later, filters having differenttime constants depending on the traveling states are used. Further, thetime constant of the filter used when performing the filter processingon the vehicle posture value (that is, the vehicle height detectionvalue H) and the time constant of the filter used when performing thefilter processing on the eye information are different.

For example, in the stopped state, t01 is adopted as the time constantof the filter used for the filter processing of the vehicle posturevalue, and t02 is adopted as the time constant of the filter used forthe filter processing of the eye information. For example, in theacceleration state, t11 is adopted as the time constant of the filterused for the filter processing of the vehicle posture value, and t12 isadopted as the time constant of the filter used for the filterprocessing of the eye information. For example, in the constant speedtraveling state, t21 is adopted as the time constant of the filter usedfor the filter processing of the vehicle posture value, and t22 isadopted as the time constant of the filter used for the filterprocessing of the eye information.

At this time, the following relations (2) to (4) are established foreach time constant.

t 01<t 02  (2)

t 11<t 12  (3)

t 21<t 22  (4)

That is, each time constant of the filter for the vehicle posture valueis smaller than each time constant of the filter for the eyeinformation. That is, since the change in the eyes is considered to beslower than the change in the vehicle posture value, the eye informationis averaged over a longer period of time than the vehicle posture value.

Further, the following relation (5) also holds for each time constant.

(t 01,t 02)<(t 21,t 22)<(t 11,t 12)  (5)

That is, in the stopped state, the time constants of the filter used forfiltering the vehicle posture value and the filter used for filteringthe eye information are made the smallest and updated earliest comparedwith the constant speed traveling state and the acceleration state (thatis, processed fastest). In the constant speed traveling state, each ofthe time constants is made larger (for example, slightly larger) than inthe stopped state, and processing is performed over time (for example,slightly over time). In the acceleration state, each of the timeconstants is made the largest as compared with the case of the stoppedstate and the constant speed traveling state, and the processing takesthe longest time.

In this way, the time constants of the filter used for the filterprocessing of the vehicle value are set larger in the order of thestopped state, the constant speed traveling state, and the accelerationstate. Moreover, the time constants of the filter used for the filterprocessing of the eye information are also set larger in the order ofthe stopped state, the constant speed traveling state, and theacceleration state.

A well-known low-pass filter (that is, LPF) may be used instead of themoving average filter. In this case as well, the time constant of theLPF is changed according to the traveling state and the processingtarget in the same manner as the time constant is changed according tothe traveling state and the processing target by the moving averagefilter.

The eye information acquisition unit 71 is configured to acquire the eyeinformation (that is, eye position information) indicating the positionof the driver's eyes. The eye information acquisition unit 71 acquiresthe positions of the eyes in the vertical direction and the front-reardirection based on the signal from the driver detection unit 9.

The driver's eye point has mechanical characteristics of a spring, amass, and a damper when viewed from the vehicle seat, and the frequencycharacteristics thereof are different from the frequency characteristicsof the vehicle posture value. Therefore, in the present embodiment, asdescribed above, the signal indicating the eye information has differenttime constant from the time constant of the filter that processes thevehicle posture value, and is processed using each filter of t02, t12,t22 set according to the traveling state.

The display position correction unit 73 is configured to correct thedisplay position of the AR image to be superimposed on the scenery inthe projection area 23 in the windshield 21 based on the vehicle posturevalue processed by the filter processing unit 69 for the signalindicating the vehicle posture value acquired by the posture valueacquisition unit 65 (that is, the processed vehicle posture value), thevehicle characteristic value G acquired by the characteristicacquisition unit 67, and the eye information processed by the filterprocessing unit 69 for the signal indicating the eye informationacquired by the eye information acquisition unit 71 (that is, theprocessed eye information).

That is, when correcting the display position, a comprehensivecorrection amount is used. The comprehensive correction amount is avalue taking into account a pitch correction amount according to thevehicle pitch angle θ, which is the correction amount calculated basedon the vehicle posture value filtered according to the traveling stateand the vehicle characteristic value G, and an eye correction amountcalculated by the filtered eye information.

Then, based on this comprehensive correction amount, the projectionposition (that is, the reference projection position) of the AR image inthe projection area 23 generated by the information generation unit 61is corrected.

[1-3. Control processing] Next, the control processing performed by thedisplay control device 3 will be described with reference to theflowchart of FIG. 6. This processing is executed when the power supplyto the HUD device 19 is started and the HUD device 19 becomes a statewhere displaying is enabled.

<Overall processing>

As shown in FIG. 6, in S 100, the display control device 3 acquiressignals from the vehicle speed sensor 31, the acceleration sensor 33,and the sensors 35 for detecting the output torque of the behaviordetection unit 7. That is, signals indicating the traveling state (thatis, a vehicle state) of the vehicle 2 such as a vehicle speed state andan acceleration state are acquired.

In the following S110, the signal from the height sensor 37 is acquired.Specifically, a signal indicating a vehicle height detection value Hindicating a displacement amount of the suspension (that is, a signalindicating a vehicle posture value) is acquired.

In the following S120, the signal from the driver detection unit 9 isacquired. That is, a signal indicating the position information (thatis, eye information) of the driver's eyes is acquired.

In the following S130, the vehicle state (that is, the traveling state)is determined. That is, as described above, the vehicle 2 is determinedwhether in the stopped state, the acceleration state, or the constantspeed traveling state based on the signals from the vehicle speed sensor31, the acceleration sensor 33, and the sensors 35.

Here, it is assumed that the acceleration state includes not only thecase of having a positive acceleration but also the case of having anegative acceleration (that is, a deceleration state).

Here, when it is determined that the vehicle is in the stopped state,the process proceeds to S140, when it is determined that the vehicle isin the acceleration state, the process proceeds to S170, and when it isdetermined that the vehicle is in the constant speed traveling state,the process proceeds to S200. In other cases, for example, the processmay return to S100.

Since it is determined that the vehicle is in the stopped state, inS140, the time constants of the moving average filter (that is, thefilter) are set to t01 and t02 as described above are prepared. That is,filters with different time constants are prepared. In addition, t01<t02is satisfied.

In the following S150, the filter processing using the filter having thetime constant of t01 is performed on the signal indicating the vehicleposture value, specifically, the signal indicating the vehicle heightdetection value H acquired from the height sensor 37.

In the following S160, the filter processing using the filter having thetime constant of t02 is performed on the signal indicating the eyeinformation, and the process proceeds to S230.

On the other hand, since it is determined that the vehicle is in theacceleration state, in S170, the time constants of the filter are set tot11 and t12 as described above are prepared. That is, filters withdifferent time constants are prepared. In addition, t11<t12 issatisfied.

In the following S180, the filter processing using the filter having thetime constant of t11 is performed on the signal indicating the vehicleposture value, specifically, the signal indicating the vehicle heightdetection value H acquired from the height sensor 37.

In the following S190, the filter processing using the filter having thetime constant of t12 is performed on the signal indicating the eyeinformation, and the process proceeds to S230.

On the other hand, since it is determined that the vehicle is in theconstant speed traveling state, in S200, the time constants of thefilter are set to t21 and t22 as described above are prepared. That is,filters with different time constants are prepared. In addition, t21<t22is satisfied.

In the following S210, the filter processing using the filter having thetime constant of t21 is performed on the signal indicating the vehicleposture value, specifically, the signal indicating the vehicle heightdetection value H acquired from the height sensor 37.

In the following S220, the filter processing using the filter having thetime constant of t22 is performed on the signal indicating the eyeinformation, and the process proceeds to S230.

Note that t01, t02, t11, t12, t21, and t22 have the relationship of theabove-mentioned formula (5).

In S230, the correction amount of the display position is calculated.The process of calculating the correction amount of the display positionwill be described in detail in the flowchart of FIG. 7 described later.

In the following S240, the display position of the HUD device 19 iscorrected by using the correction amount.

That is, the AR image generated by the information generation unit 61 issupplied to the HUD device 19 after the projection position is correctedby the correction amount. Specifically, the projection position (thatis, the reference projection position) of the AR image in the projectionarea 23 generated by the information generation unit 61 is corrected inaccordance with the correction amount (that is, the comprehensivecorrection amount), and the projection of the AR image is performedbased on the corrected projection position.

In the following S250, it is determined whether or not the terminationcondition for terminating the present processing is satisfied. When anaffirmative determination is made, the present processing is terminated.When a negative determination is made, the process returns to S100. Itshould be noted that, for example, when the ignition switch is turnedoff or when a command to stop the operation of the HUD device 19 isinput, it is determined that the termination condition is satisfied.

<Correction amount calculation processing>

Next, the calculation processing of the correction amount of the displayposition performed in S230 will be described in detail based on theflowchart of FIG. 7.

As shown in FIG. 7, in S300, the vehicle characteristic value G isacquired from the characteristic storage unit 17.

In the following S310, the signal of the height sensor 37 filtered inS150 (that is, the vehicle height detection value H) is acquired.

In the following S320, based on the map information stored in the mapstorage unit 11, the current position acquired from the positioning unit13, that is, the gradient information ψ representing the road gradientof the road on which the subject vehicle 2 is traveling is acquired. Thegradient information iv here represents a longitudinal gradient.

Next, in S330, the vehicle pitch angle θ, which is the inclination angleof the vehicle body in the front-rear direction with respect to thehorizontal plane, is calculated using the following formula (6) based onthe vehicle characteristic value G acquired in S300, the vehicle heightdetection value H acquired in S310 (that is, the vehicle heightdetection value H after filtering), and the gradient information ψacquired in S320. Note that G (H) is a vehicle pitch angle estimatedfrom the vehicle characteristic value G using the vehicle heightdetection value H. C is an experimentally determined constant.

θ=G(H)+C·ψ  (6)

In the following S340, the eye position information representing the eyeposition of the driver filtered in the S160 (that is, the eyeinformation after the filter processing) is acquired. The eye positioninformation is represented by, for example, the amount of deviation fromthe reference eye position. As will be described later, the amount ofdeviation of the position of the eye can be expressed by, for example,the angle of rotation of the eye from a reference point (for example, asuperimposed object).

In the following S350, the correction amount of the projection positionof the AR image in the projection area 23 is calculated based on thevehicle pitch angle θ calculated in S330, the eye position information(for example, the angle of rotation) acquired in S340, and thethree-dimensional position of the object on which the AR image issuperimposed (that is, the superimposed object).

That is, by adding the angle information of the eye (that is, the angleof rotation of the eye) indicated by the position information of the eyeto the vehicle pitch angle θ, the rotation angle of the mirror 47 iscorrected such that the AR image in the projection region is positionedon a straight line from the position of the eye to the object.

The eye angle information is information indicating the difference inangle between the position of the eye and the position of the object dueto the position of the eye shifting in the vertical or front-reardirection, and is calculated from the positions of the eye and theobject.

[1-4. Procedure for calculating amount of correction]

Next, the outline of the process for calculating the correction amountof the projection position of the AR image performed in FIG. 7 will bedescribed with reference to FIG. 8.

Here, for the sake of simplification of the explanation, the case wherethe gradient information is ψ=0° will be described.

A case where the vehicle 2 causes pitching and the vehicle body tiltsforward will be described. The eye position of the driver is representedby Ei, the projection area 23 is represented by Di, and the positionwhere the light imaged as a virtual image is emitted, that is, theposition of the projector 43 is represented by Si. Note that i=0indicates a position when the vehicle pitch angle is 0°, and i=1indicates a position when the vehicle pitch angle is θ.

When the vehicle 2 tilts forward due to pitching, the projection regionD0 of the windshield 21, which is the display surface (that is, the HUDdisplay surface) of the HUD device 19, and the light emission positionS0 define the vehicle center of gravity J as the center of rotation andmove to the positions D0 to D1 and S0 to 51, respectively, rotated by anangle θ (that is, the vehicle pitch angle θ).

The driver's eye position E0 indicates the position of the vehicle 2leaning forward, and the driver's eye position E1 indicates the positionwhen the vehicle 2 tilts forward at the vehicle pitch angle θ.

When the vehicle pitch angle is 0°, that is, when the eye position is atE0, the AR image superimposed on the object (that is, the superimposedobject) O needs to be projected at the position Pa that intersects astraight line connecting the eye position E0 and the object O and theprojection region D0.

When only the vehicle 2 is considered in a case where the vehicle pitchangle is θ, that is, when only the vehicle 2 is tilted and the eyeposition is at E0, the AR image superimposed on the object O needs to beprojected at the position Pb that intersects a straight line connectingthe eye position E0 and the object O and the projection area D1.

That is, the projection position Pb in the projection area D1 is aposition shifted upward as compared with the projection position Pa inthe projection area D0.

Further, when the vehicle 2 is tilted forward and the actual eyeposition is the eye position E1, the AR image superimposed on the objectO needs to be projected on the position Pc in the projection area D1.

That is, the projection position Pc when the eye position is displacedis shifted downward as compared with the projected position Pb when theeye position is not displaced.

As shown in FIG. 9, since the position of the eye can be detected by thecamera of the driver detection unit 9, it is possible to acquire each ofthe angles θ1 and θ2 that is an angle between the position of the object(for example, the horizontal position) and the position of the eye. Notethat θ1 is the angle before rotation and θ2 is the angle after rotation.Therefore, the amount of movement (that is, the angle of rotation) whenthe eye moves from E0 to E1 can be acquired by θ2-θ1.

In this way, by summing the correction amount according to the vehiclepitch angle θ, that is, the deviation amount from Pa to Pb, and thecorrection amount caused by the deviation of the eye position, that is,the deviation amount from Pb to Pc (that is, θ2-θ1), the correctionamount of the projection position of the AR image is calculated.

Here, the correction amount is indicated by an angle. Alternatively, thecorrection amount may be indicated by the correction amount of theposition in the vertical direction of the LCD panel or the like or theposition of the pixel, since the position in the LCD panel (for example,the distance in the vertical direction and the number of pixels), andtherefore the position in the projection area 23 (for example, thedistance in the vertical direction and the pixels) is corrected.

[1-5. Vehicle characteristic value]

Next, the vehicle characteristic value G stored in the characteristicstorage unit 17 will be described.

Using the simple two-wheel model shown in FIG. 10, the relationshipbetween the detected value of the height sensor 37 and the vehicle pitchangle is theoretically derived. Here, the distance from the front wheelto the position of the center of gravity of the load applied to thevehicle 2 is defined as a, and the distance from the front wheel to therear wheel is defined as b. The spring constant of the front suspensionis defined as Kf, the spring constant of the rear suspension is definedas Kr, the displacement amount of the front suspension is defined as xf,and the displacement amount of the rear suspension is defined as xr. Theload applied to the vehicle 2 is defined as F, and the vehicle pitchangle, which is the tilt angle of the vehicle body due to this load, isdefined as θ.

Formula (7) is obtained from the balance of forces, and formula (8) isobtained from the balance of moments around the front.

(Equation 2)

F=K _(f) ·x _(f) +K _(r) ·x _(r)  (7)

a·F−b·x _(r) ·K _(r)=0  (8)

Solving formula (8) for xr gives formula (9), and substituting formula(9) into formula (7) for rearrangement gives formula (10).

$\begin{matrix}( {{Equation}3} ) &  \\{x_{r} = \frac{a \cdot F}{b \cdot K_{r}}} & (9)\end{matrix}$ $\begin{matrix}{x_{f} = {\frac{F}{K_{f}}( {1 - \frac{a}{b}} )}} & (10)\end{matrix}$

At this time, the vehicle pitch angle θ is expressed by the formula(11), and by solving this with respect to θ, the formula (12) can beobtained.

$\begin{matrix}( {{Equation}4} ) &  \\{{\tan\theta} = \frac{x_{r} - x_{f}}{b}} & (11)\end{matrix}$ $\begin{matrix}{\theta = {\tan^{- 1}\frac{x_{r} - x_{f}}{b}}} & (12)\end{matrix}$

That is, when xf is obtained by the height sensor 37, F can be obtainedfrom the formula (10), and xr is calculated from the formula (9) usingF. Similarly, when xr is obtained by the height sensor 37, F can beobtained from the formula (9), and xf is calculated from the formula(10) using F.

The vehicle pitch angle θ can be obtained by using the values of xf andxr and the formula (12). From this relationship, it can be seen thatthere is a corresponding relationship between the detection value of theheight sensor 37 (that is, xf or xr), that is, the vehicle heightdetection value H, and the vehicle pitch angle θ.

[1-6. Effects]

According to the present embodiment detailed above, the followingeffects may be obtained.

(1 a) In the present embodiment, the characteristics of the filter usedby the filter processing unit 69 are set according to the travelingstate of the vehicle 2, and the display position when the AR image to berecognized as a virtual image is superimposed on the scenery in theprojection area 23 of the windshield 21 is corrected based on thevehicle posture value (that is, the vehicle height detection value H) inwhich the filter process is performed using the set filter and thevehicle characteristic value G acquired by the characteristicacquisition unit 67.

According to such a configuration, when the display position of the ARimage is corrected based on the vehicle posture value and the vehiclecharacteristic value, the vehicle posture value in which the filterprocess is performed using the filter set according to the travelingstate of the vehicle 2. Thus, when the AR image is displayed, theconfiguration can suppress the flickering of the display and quicklycorrect the display position.

Specifically, when the vehicle 2 is in the acceleration state, a filterhaving a large time constant is adopted as compared with the case wherethe vehicle 2 is in the stopped state or the constant speed travelingstate. Thus, the configuration, in the acceleration state, can suppressthe flickering of the display, and, in the stopped state or the like,quickly correct the display position.

Since the time constant of the filter used in the constant speedtraveling state is a value between the acceleration state and thestopped state, it is possible to be moderately consistent of reducingthe flicker of the display and quickly correcting the display position.

For example, as shown in FIG. 11, as the vehicle speed increases, thevehicle pitch angle θ (that is, the pitch angle in the figure)frequently fluctuates and the amount of fluctuation in the pitch anglealso increases. Therefore, the display position fluctuates frequentlyand the amount of fluctuation increases, which makes the driver feelflickering.

Therefore, in the present embodiment, since the characteristic (forexample, time constant) of the filter used for the filter processing ofthe vehicle posture value is changed in the traveling state of thevehicle 2, the configuration can perform appropriate filteringprocessing according to the traveling state. In this way, by adopting afilter having appropriate characteristics according to the travelingstate, the configuration can achieve both reduction of display flickerand quick correction of the display position.

(1 b) Further, in the present embodiment, the filter for the eyeinformation that processes the eye information is configured to have acharacteristic different from the filter used for the vehicle posturevalue.

Specifically, the time constant of the filter that filters the eyeinformation is set to be greater than the time constant of the filterthat filters the vehicle posture value. Then, when the display positionis corrected, this eye information is also taken into consideration inthe correction.

As described above, by using the filter in which the time constantsuitable for the change of the eye is set, there is an advantage thatthe flicker of the display is further suppressed.

[2. Other embodiments] Although the embodiments of the presentdisclosure have been described above, the present disclosure is notlimited to the embodiments described above, and various modificationscan be made to implement the present disclosure.

(2 a) In the present disclosure, the time constant of the filter usedwhen the vehicle is stopped or when the vehicle is traveling at aconstant speed may be smaller than the time constant of the filter usedwhen the vehicle is accelerating.

(2 b) In the present disclosure, the time constant of the filter usedwhen the vehicle is stopped may be smaller than the time constant of thefilter used when the vehicle is traveling at a constant speed.

(2 c) In the present disclosure, the time constant for processing theeye information is greater than the time constant of the filter used forprocessing the vehicle posture value.

(2 d) In the above embodiment, the time constant of the filter used forprocessing the eye information is set to be larger than the timeconstant of the filter used for processing the vehicle posture value.Alternatively, the time constant of the filter used for processing theeye information may be same as the time constant of the filter used forprocessing the vehicle posture value.

(2 e) Further, only the time constant of the filter used for processingthe vehicle posture value may be changed according to the travelingstate.

That is, the filter used for processing the eye information is notlimited, and may not be changed according to the traveling state, forexample.

(2 f) The display control device and the technique of the display deviceaccording to the present disclosure may be achieved by a dedicatedcomputer provided by constituting a processor and a memory programmed toexecute one or more functions embodied by a computer program.

Alternatively, the display control device and the technique of thedisplay device according to the present disclosure may be achieved by adedicated computer provided by constituting a processor with one or morededicated hardware logic circuits.

Alternatively, the display control device and the technique of thedisplay device according to the present disclosure may be achieved usingone or more dedicated computers constituted by a combination of aprocessor and a memory programmed to execute one or more functions and aprocessor formed of one or more hardware logic circuits.

Further, the computer program may be stored in a computer-readablenon-transitory tangible storage medium as instructions to be executed bya computer. The technique for realizing the functions of the respectiveunits included in the display control device does not necessarily needto include software, and all of the functions may be realized with theuse of one or multiple hardware.

(2 g) The multiple functions of one component in the above embodimentmay be realized by multiple components, or a function of one componentmay be realized by the multiple components. In addition, multiplefunctions of multiple components may be realized by one component, or asingle function realized by multiple components may be realized by onecomponent. A part of the configuration of the above embodiment may beomitted. At least a part of the configuration of the above embodimentmay be added to or replaced with another configuration of the aboveembodiment.

(2 h) The present disclosure can be realized in various forms, inaddition to the display control device described above, such as a systemincluding the display control device as a component, a program forcausing a computer to function as the display control device, anon-transitory tangible storage medium such as a semiconductor memorystoring the program, or a display control method.

What is claimed is:
 1. A display control device comprising: aninformation generation unit configured to set a display position of animage, as a virtual image, to be recognized by a driver of a vehiclesuch that the image is superimposed on a scenery in front of thevehicle, the image being displayed on a display unit that is disposed infront of a driver seat of the vehicle and enables the driver torecognize the scenery, a traveling state acquisition unit configured toacquire a traveling state of the vehicle; a posture value acquisitionunit configured to acquire a vehicle posture value indicating a postureof the vehicle; a characteristic acquisition unit configured to acquirea vehicle characteristic value indicating a characteristic of thevehicle from a characteristic storage unit that stores the vehiclecharacteristic value; a filter processing unit configured to perform afilter processing with a filter on the vehicle posture value acquired bythe posture value acquisition unit; and a display position correctionunit configured to calculate a correction amount for correcting thedisplay position at which the image is superimposed on the scenery basedon the vehicle characteristic value processed by the filter processingunit and the vehicle characteristic value acquired by the characteristicacquisition unit, wherein the filter processing unit sets acharacteristic of the filter according to the traveling state of thevehicle acquired by the traveling state acquisition unit, and performsthe filter processing with the filter set.
 2. The display control deviceaccording to claim 1, further comprising an eye information acquisitionunit configured to acquire eye information indicating a position of aneye of the driver, wherein a filter for processing the eye informationhas a characteristic different from the characteristic of the filter forthe filter processing on the vehicle posture value, and the displayposition correction unit corrects the display position based on the eyeinformation processed by the filter for the eye information.
 3. Thedisplay control device according to claim 1, wherein the traveling stateacquisition unit acquires the traveling state of the vehicle based on aspeed of the vehicle or a tire output.
 4. The display control deviceaccording to claim 1, wherein the posture value acquisition unit isarranged at least one of a front part and a rear part of the vehicle,and acquires the vehicle posture value based on a signal from a changeamount detection unit configured to detect a change amount of a vehicleheight.
 5. A display control device comprising: a processor configuredto set a display position of an image, as a virtual image, to berecognized by a driver of a vehicle such that the image is superimposedon a scenery in front of the vehicle, the image being displayed on aprojection area that is disposed in front of a driver seat of thevehicle and through which the scenery is recognized, acquire a travelingstate of the vehicle; acquire a vehicle posture value indicating aposture of the vehicle; acquire a vehicle characteristic valueindicating a characteristic of the vehicle from a characteristic storagethat stores the vehicle characteristic value; perform a filterprocessing with a filter on the vehicle posture value; calculate acorrection amount for correcting the display position at which the imageis superimposed on the scenery based on the vehicle characteristic valueafter the filter processing and the vehicle characteristic value; andset a characteristic of the filter according to the traveling state inorder to perform the filter processing with the filter set.